1. Field of the Invention
The present invention generally relates to a cling packaging film. More specifically, the present invention is directed to a transparent, cling packaging film for wrapping consumer products, especially fresh meat and produce. The film of the invention comprises at least two layers, a skin layer principally comprising linear low density polyethylene and a core layer principally comprising a copolymer of ethylene and an ethylenically unsaturated polar comonomer and also containing an elastomeric polymer. These films are often referred to as PVC food wrap replacement films.
2. Description of the Background
Many food products, particularly fresh meat and produce, are wrapped in transparent, thin film. This film must be both transparent to provide an aesthetically pleasing product for the consumer and sufficiently strong to provide the protection desired. For example, in meat packaging, a crystal clear, transparent film is desired to provide a visually attractive wrapping for fresh meat typically placed on a plastic or foam package and then wrapped with the film. The film must be sufficiently strong to withstand the wrapping process, whether automated or manual, wherein the film is rapidly stretched about the product and sealed by clinging to itself or by heat sealing. Further, the film when stretched about the food product must provide protection from puncture upon deformation by being poked with fingers or other packages, and the film must exhibit good recoverability so that the deformation quickly disappears.
Fresh foods, particularly meat products, are wrapped automatically on processing lines with cling wrap film. The procedure involves the intermittent, high speed removal of film from a supply roll, the pushing of a tray filled with food upward until it impacts against the film, the stretching of the film around the tray to the lower side thereof and the sealing of the film. The film may be sealed by clinging to itself or by heat sealing the edges of the film. The elasticity of the film must maintain the stretched film in a tight fit about the product. These films must be transparent, tear resistant, puncture resistant and exhibit good recovery from deformation.
Polyvinyl chloride (PVC) film has long been the film of choice in the food wrap industry. However, the food wrap industry has expressed a desire for an alternative, PVC-free replacement film. It has been difficult to formulate compositions based on olefinic polymers for making a cling wrap film. These compositions must both satisfy the characteristics described above and satisfy the many food law requirements.
Films made of low density polyethylene have been used in stretch packaging. These films are often rigid, have low elongation and low tear strength. Although ethylene vinyl acetate films are free from many of the previously mentioned problems, EVA films suffer from poor tear resistance. In order to overcome these problems, laminated films comprising two or more layers of different materials having differing characteristics have been developed. Many patents have been directed to stretch and cling films comprising multiple layers of these and other principal and minor components. However, none of those patents have solved the long felt but unfulfilled need for a satisfactory PVC replacement film. None of these films have exhibited the desirable combination of tear strength, recoverability, optical clarity, sealability and other attributes important to a PVC replacement film.